1. Nucleic Acids
NUCLEIC ACIDS AND DNA

2. Standard Biology What did we learn from POGIL?
GOT
NEED

3. Rosalind Franklin First to discover that DNA must be 3-D
Not in notes
Rosalind Franklin
First to discover that DNA must be 3-D
Used X-ray diffraction and chromatography

4. The Double Helix

5. Watson and Crick
1953 – Discovered the structure of DNA (double helix model)
- DNA is made of two chains of nucleotides joined at the nitrogen bases by hydrogen bonds
Double Helix Model
(twisted ladder)

6. Nucleotide Structure
DNA (a nucleic acid) is a polymer made up of repeating sub-units called NUCLEOTIDES
Three Parts of nucleotides:
Nitrogen BASE
Deoxyribose Sugar
Phosphate group

7. TYPES OF SUGARS Two types of sugars in the nucleic acids are:
DNA: Deoxyribose RNA : Ribose
Nucleic Acid
Nucleic Acid

8. Nitrogen Bases 4 Possible Base pairs in DNA Adenine Cytosine Guanine
Thymine
RNA base!

9. BASE PAIRING RULE The amount of A=T and amount of G=C
In double stranded DNA weak hydrogen bonds connect
G - C and A - T

10. Complementary Base Pairing
Parent Strand: A T G G G C C A A G G G C
Complementary Strand ______________________________________________
“The “Complementary” strand is the opposite side of a DNA ladder.
In DNA, A is always opposite T, and G is always opposite C.
WATCH ME!
If a DNA strand contains 20% Thymine, then…
how much Adenine will it contain?
how much Cytosine will it contain?
how much Guanine will it contain?

11. WHITE BOARD - Practice Again
2) If a DNA strand contains 30% Guanine, then…
how much Adenine will it contain?
how much Cytosine will it contain?
how much Thymine will it contain?

12. WHITE BOARD – Practice Last Time
3) f a DNA strand contains 15% Thymine, then…
how much Adenine will it contain?
how much Cytosine will it contain?
how much Guanine will it contain?

13. Let’s check our POGIL

15. Phosphate Group
In a DNA nucleotide, the Phosphate group is composed of one atom of PHOSPHORUS surrounded by four atoms of OXYGEN

16. Shape of DNA
Double Helix
Twisted Ladder
Sugar-Phosphate Backbone

17. Essential Questions WHITE BOARD!
1. What is the shape of DNA? 2. Who discovered DNA’s structure? 3. What are the sub-units of DNA called? 4. What are the 3 parts to a nucleotide? 5. Which nucleotides bind together in DNA?

18. Essential Skill WHITE BOARD!
DRAW and LABEL a nucleotide and its 3 parts without looking at your notes!

19. Clear your Board!

20. Essential Questions Write it Down!
1. What is the shape of DNA?
2. Who discovered DNA’s structure?
3. What are the sub-units of DNA called?
4. What are the 3 parts to a nucleotide?
Which nucleotides bind together in DNA?
DRAW and LABEL a nucleotide and its 3 parts.

21. Video

22. DNA REPLICATION DNA replication involves making an exact copy of DNA.
Happens during Interphase of cell cycle, BEFORE cell division (before mitosis or meiosis)

23. DNA REPLICATION Process of DNA reproducing an exact copy of itself
Enzymes (helicase) break the hydrogen bonds and DNA molecule “unzips”
Free nucleotides in the cytoplasm binds to the single strands by base pairing (A-T and G-C)
An enzyme (DNA polymerase) binds the new base pairs together to form 2 new identical strands
Proofreading enzymes then check the new DNA for mistakes

24. DNA Replication is Semi-conservative
Semi = “half”
Conserve = “to save”
When DNA makes a copy of itself, it uses the parent strand (“old” DNA) as a template to make the “new” strand.
End Result = 2 identical DNA molecules each with ½ old (parent) DNA and ½ new

25. Semi-conservative Replication

26. Mutations Mistakes made in the genetic code
(either during DNA replication or protein synthesis)
2 specific types of mutations:
POINT mutation-
one base is substituted for another
Original: GGT ATC GGA TTA
Replicated: GGC ATC GGA TTA
2. FRAME SHIFT mutation-
one base is added or deleted and it shifts sequence
Original: GGT ATC GGA TTA
Replicated: GGA TCG GAT TA
- T was deleted thus causing the whole molecule to shift
Which type of mutation has the greater effect on the DNA?

27. Essential Questions Write it Down!
What is Replication?
What are the steps to replication?
What organic molecule controls all steps in the replication process?

28. Worksheet Practice
Complete BOTH sides of the worksheet to review DNA structure and the process of DNA replication.